The packaging of liquids and particularly the resealing of opened liquid packets has always had the twin challenges of operational simplicity and reliable leak prevention. Whatever the design it must be intuitively easy to operate by users with widely ranging physical abilities; equally important is absolute leakage control which not only prevents product loss but also avoids damage to surrounding materials and circumstances. Above all, the design must provide these features in the form of a very low cost, small, disposable packet. Numerous inventive designs have been put forth over many years to meet these well recognized challenges. The following are representative of the current art.
Salfisberg, U.S. Pat. No. 2,325,921 (1943) describes a polymeric packet for distribution of tablets or liquids. The design includes a material reservoir, a discharge neck, a matchbook-style cover that when closed and held folds the discharge neck so as to prevent accidental discharge. This design has no controlling barrier feature or restrictive passage so the relatively large discharge channel permits substantial leakage whenever even minor incidental external pressure is applied to the liquid reservoir.
Schneider, U.S. Pat. No. 2,976,988 (1961) describes a polymeric packet for distribution of tablets or liquids. Two chambers, reservoir and distribution, are connected by a passage designed to control liquid exchange by simple stretch tension produced by the polymeric walls of the packet, opened under fluidic pressure, and resealing when the fluidic pressure is released. No other resealing features such as a fold are provided and application of inadvertent pressure to the liquid through the walls, such as found in a purse or pocket, is more than sufficient to produce a substantial product discharge with subsequent loss and damage.
Schneider, U.S. Pat. No. 3,224,640 (1965) describes a flexible polymeric packet with an extended discharge channel that is folded over and held against the packet by placing the discharge end in a slit pocket formed as part of the packet wall. This one chamber design absent a controlling barrier feature and restrictive passage is very prone to leakage particular along the channel edges where the fold and side seals meet but fail to provide effective closure.
Amneus, U.S. Pat. No. 4,163,509 (1979) describes a dispensing container with an elongated discharge spout ending in a tension curl valve designed to uncurl and release fluid when a stripping action is applied to the length of the discharge spout. Due to the relatively stiff tension required to maintain the curl for leakage control, the design is better adapted to wall hanging and mechanical operation and precludes the convenience of a pocket carried version.
Herzig, U.S. Pat. No. 4,252,257 (1981) describes a flexible container employing a transverse pinch-off valve at the discharge slit that opens when pressure is applied to key areas of the container adjacent to a pinch-off line. Practice has shown the tension of the valve quickly fatigues and leakage results. Ease of manipulation has also proven problematic.
Imer, U.S. Pat. No. 5,228,782 (1993) describes a polymeric sachet with a liquid reservoir and narrow outlet channel through which the liquid is discharged. The sachet is resealed by folding the strap in which the narrow channel is located at a 45° angle and fitting the strap extension into a holding slit thus sealing the channel. In practice the strap manipulation is cumbersome to operate and prone to accidental discharge and leakage. Additionally the lack of a distribution chamber to control pressure discharge and dose measurement makes dispersement messy and erratic.
Farmer, U.S. Pat. No. 6,244,468 (2001) describes a liquid sachet with two chambers formed by seals, a connecting inlet, and an exit point resealable by twin tension folds traversing the opening that unfold under hydraulic pressure to disperse the liquid. The tension necessary to hold the folds shut is necessary slight so as to appropriately respond to an opening pressure that needs to remain within moderate limits, this requirement and the lack of any fold holding means makes the folds vulnerable to accidental opening, discharge, and leakage when inadvertently manipulated by movements and conditions typically found in a pocket, briefcase, or purse.
Harper, U.S. Pat. No. 7,004,354 (2006) describes a self-sealing polymer packet with reservoir and dispersement chambers, a traversing barrier seam forming the chambers, and an active choke valve in the barrier seam that restricts pressurized liquid passage unless opened by intentional contortion of the packet walls. In practice the design presents operational challenges to users with small hands, arthritic fingers, or limited dexterity. Additionally, some users disbelieve a miniscule choke valve can adequately reseal the packet, preferring a more obvious and robust closure system to prevent leakage.
The present invention recognizes the numerous seal variations found in the foregoing prior art and specifically addresses their individual and collective disadvantages and shortcomings. Salfisberg's matchbook packaging with a fold closure held in place by a cover is simple, somewhat intuitive, cost effective, but leaks badly. Schneider '640 and Imer disclosed fold-and-hold designs that are both cumbersome to operate and prone to leakage and discharge. Schneider '988 introduced the bi-chamber and contolling barrier features together with cost effectiveness but failed to provide a robust closure system against leakage. Amneus, Herzig and Farmer all employed spout closure designs that relied upon material tension to control leakage, such designs are prone to accidental external manipulation that allows leakage, particularly in small packets intended for pocket or purse carrying. The Harper packet with the active choke seal design provides effective measurement and dose dispersal, together with cost effectiveness and good leak protection, but opening the seal is not easy for all users. Despite all these efforts there is still an unmet need for a novel closure system that makes secure, resealable liquid packets a simple reality for all users.